JP2514480Y2 - Tandem negative pressure booster - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to a tandem type negative pressure booster used for operating a brake master cylinder of an automobile, and more particularly, to a booster shell. A partition plate is fixedly installed to partition the inside into a front shell chamber and a rear shell chamber, and the front shell chamber is partitioned into a front front negative pressure chamber and a rear front working chamber that are connected to a negative pressure source. A piston boss, which is slidably supported by the partition plate and connected to the output rod, includes a front booster piston and a rear booster piston that partitions the rear shell chamber into a front rear negative pressure chamber and a rear rear working chamber. And a valve cylinder that projects from the rear end and is slidably supported by the rear wall of the booster shell is connected to the piston boss integrally, and the inside of the valve cylinder is connected to both negative pressure chambers. Operates both the first port and the inside of the same cylinder And a second port that communicates between the front negative pressure chamber and the valve cylinder, and a radial port that communicates between the axial port and the rear negative pressure chamber. The input rod which can be moved back and forth is provided in the valve cylinder, and the second port is provided with a first port according to the forward and backward movement of the input rod.
The present invention relates to an improvement of the one provided with the valve for switching the communication between the port and the atmosphere.

(2) Conventional Technology Such a negative pressure booster is already known, as disclosed, for example, in Japanese Utility Model Laid-Open No. 62-121160.

(3) Problem to be Solved by the Invention In such a negative pressure booster, in order to return the negative pressure booster from the operating state to the non-operating state, the negative pressure booster is moved backward through the first and second ports by the backward operation of the input rod. When the chamber is communicated with both the front and rear working chambers, the air occupying both working chambers up to that point is discharged from the second port to the second port by the strong suction action of the negative pressure source connected to the front negative pressure chamber. It is rapidly sucked into the front negative pressure chamber through the 1-port axial port. At this time, air flows through the axial port from the valve cylinder side to the front negative pressure chamber side at a high speed, but in the one described in the above publication, the air flow direction is suddenly increased in the bent portion formed in the middle of the axial port. Changes to a large turbulent flow, which causes operating noise (wind noise).
It has been clarified by the present inventors that it is one of the causes.

Therefore, in order to solve such a problem, it is conceivable to make the axial port substantially linear over its entire length, for example, as shown in FIG. 7, but even in that case, as shown in FIG. It was found that part of the air flowing through 30A circulates toward the port 30R in the radial direction and causes a vortex c near the opening of the port 30R, which contributes to operating noise (wind noise).

The present invention has been proposed in view of the above, and when air flows through the axial port of the first port at a high speed, no vortex occurs in the axial port itself or in the vicinity of the opening of the radial port. Thus, an object is to provide a tandem type negative pressure booster with low operating noise.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above-mentioned object, the present invention forms the axial port of the first port in a substantially linear shape over the entire length thereof, and Of the half portion of the peripheral wall on the outer side in the radial direction of the piston boss, the portion on the front side of the opening edge on the axial port side of the radial port is displaced outward in the radial direction from the rear side portion, and a step is formed on both portions. Is provided.

(2) Action When air flows through the axial port from the valve cylinder side to the front negative pressure chamber side at high speed, the turbulent flow in the axial port itself is related to the fact that the axial port is substantially linear. The generation of eddies and vortices is suppressed as much as possible. At that time, even if part of the high-speed airflow that flows in a substantially straight line tries to wrap around to the radial port, of the axial port peripheral wall outer half of the piston boss, the radial port axial port Since there is a step between the part on the front side of the side opening edge and the part on the rear side of the side opening edge, the above-mentioned air flow attempting to wrap around the radial port easily jumps over the radial port with its inertial force and moves in the axial direction. The transition to the downstream side of the port, that is, to the front side, can be smoothly performed, and the generation of vortices near the opening of the radial port is also suppressed.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, a brake master cylinder M operated by the booster B is mounted on the front surface of the booster shell 1 of the tandem type negative pressure booster B.

The booster shell 1 includes a pair of front and rear shell halves 1a and 1b for connecting opposing ends to each other, and is sandwiched between the two shell halves 1a and 1b to divide the inside of the booster shell 1 into a front shell chamber 2 and a rear shell chamber. The rear shell half 1b is supported by a vehicle body (not shown).

The front shell chamber 2 has a front booster piston 4 housed therein so as to be able to reciprocate back and forth, and a front part which is bonded and bonded to the rear surface thereof and is sandwiched between the front shell half 1a and the partition plate 1c. The diaphragm 5 divides a front negative pressure chamber 2a on the front side and a front operating chamber 2b on the rear side. Also, rear shell room 3
Is a rear booster piston 6 housed therein so as to be capable of reciprocating back and forth, and a rear diaphragm 7 that is polymer-bonded to the rear surface and fixed between the shell halves 1a and 1b together with the partition plate 1c. Rear negative pressure chamber 3a and rear rear working chamber
3b.

The front and rear booster pistons 4, 6 are each formed in a ring shape from a steel plate, and these are made of a synthetic resin piston boss 10 as a boss portion slidably supported on the partition plate 1c via a bush 8 and a seal member 9. Are attached to both ends as follows.

That is, the piston boss 10 is formed with a circular recess 11 whose depth reaches approximately half the length of the boss 10 at the front end face, and a flange 12 at a position slightly forward from the rear end of the outer peripheral face.
The circular concave portion 11 has a connecting tube 1 with an end wall plate 13a connected to the inner peripheral end of the front booster piston 4.
3 is fitted, and a holding plate 14 for holding the rear booster piston 6 in cooperation with the flange 12 is overlapped on the rear end face of the piston boss 10. The holding plate 14, the piston boss 10, and the end wall plate 13a are mutually connected by a plurality of (three in the figure) through bolts 15 surrounding the axis of the piston boss 10 and a nut 16 screwed to them. To be fixed.

At this time, between the front booster piston 4 and the front end face of the piston boss 10, the inner peripheral bead 5a of the front diaphragm 5 is provided.
An annular retainer 17 that covers the outer peripheral surface and the rear surface of the inner bead 5a is inserted, and between the flange 12 and the holding plate 14, a rear diaphragm 7 that wraps the inner peripheral end of the rear booster piston 6 is formed. The circumferential bead 7a is inserted. Therefore,
The front and rear booster pistons 4, 6 and the piston boss 10 are connected to each other, and at the same time, the inner peripheral beads 5a, 7a of the respective diaphragms 5, 7 are fixed to the corresponding booster pistons 4, 6.

Furthermore, to insert the through bolt 15, the piston boss 10
A seal member 19 is attached to the bolt hole 18 provided in the
As a result, communication between the front negative pressure chamber 2a and the rear working chamber 3b by the bolt hole 18 is prevented. Further, a seal member 20 surrounding the plurality of through bolts 15 is interposed between the end wall plate 13a and the piston boss 10, whereby the end wall plate 13a
Further, communication between the first and second ports 30 and 31 described below due to the contact surface gap of the piston boss 10 is prevented.

Each through-bolt 15 is disposed with its square head 15a facing the rear working chamber 3b, and a recess 21 (see FIG. 2) of the same shape into which the square head 15a fits in a non-rotatable manner is provided on the holding plate 14. It is formed. Therefore, when the nut 16 is screwed into the bolt 15 on the front negative pressure chamber 2a side, the rotation of the bolt 15 is prevented, so that the nut 16 can be securely tightened.

Using the through bolt 15 and the nut 16, the connecting cylinder 13
The seat plate 22 is superposed and bonded to the end wall plate 13a. This seat plate 22
Is provided with a plurality of seats 22a (see FIG. 3) raised above the height of the nuts 16 between the plurality of nuts 16, and a return spring is provided between the seats 22a and the front shell half 1a. 23 will be reduced. Due to the spring force of the return spring 23, the piston boss 1
0, and therefore both booster pistons 4, 6 are always biased in the backward direction. The retreat limit of both booster pistons 4 and 6 is regulated by a large number of protrusions 24 protruding on the rear surface of the rear diaphragm 7 abutting the rear wall of the booster shell 1.

A valve cylinder 25 is integrally projectingly provided at the rear end of the piston boss 10. The valve cylinder 25 is protruded from the rear wall of the booster shell 1 to cover the valve cylinder 25. It is slidably supported via a seal member 28.

The front negative pressure chamber 2a is connected via a negative pressure introducing pipe 29 to a negative pressure source V (not shown) (for example, inside an intake manifold of an internal combustion engine). The front and rear negative pressure chambers 2a and 3a are connected to the valve cylinder 25 via a bifurcated first port 30 formed in the piston boss 10.
The front and rear working chambers 2b, 3b communicate with each other, and the front and rear working chambers 2b, 3b are also formed in the piston boss 10.
Through the valve cylinder 25. And the second port 31,3
1 is a control valve 32 for the first port 30 and the rear extension cylinder 26.
The communication with the atmosphere introduction port 33 opening in the end wall 26a is alternately switched.

As clearly shown in FIG. 5, the first port 30 is an axial port 30A that extends substantially parallel to the axis of the piston boss 10 so as to communicate between the front negative pressure chamber 2a and the valve cylinder 25. When,
Branch from the middle of this axial port 30A to the rear negative pressure chamber 3a.
Composed of radial ports 30R and reaching. Of the half portion of the peripheral wall of the axial port 30A on the outer side in the radial direction of the piston boss, the front portion 30Af with respect to the opening edge of the axial port 30A side of the radial port 30R is further outward in the radial direction than the rear portion 30Ar. Between the two portions 30Af and 30Ar (therefore, at the opening edge of the radial port 30R, the front negative pressure chamber 2
A step 1 is provided between the a-side portion e ₂ and the valve cylinder 25-side portion e ₁ .

An input rod 35 connected to the brake pedal 34 is provided in the valve cylinder 25.
The control valve 32 controlled thereby is provided as follows. That is, the valve piston 38 is slidably fitted in the front portion of the valve cylinder 25, and the atmosphere introduction port is provided at the center of the valve piston 38.
The spherical front end portion 35a of the input rod 35 penetrating the 33 is fitted.
The second port 31, 31 is provided on the outer periphery of the intermediate portion of the valve piston 38.
Is formed with an annular groove 38a facing the open end of the input groove 35. By caulking the bottom wall of the annular groove 38a at several places 60 (only one of which is shown), the valve piston 38 has a spherical front end portion of the input rod 35. 35a is swingably coupled.

An annular first valve seat 40 ₁ is projectingly provided on the inner peripheral surface of the valve cylinder 25, and an annular second valve seat 40 ₂ surrounded by the annular first valve seat 40 ₁ is formed on the rear end surface of the valve piston 38. A valve body 41 cooperating with the seats 40 ₁ and 40 ₂ is arranged in the valve cylinder 25. The valve body 41 is made of rubber and has a cylindrical shape with both front and rear ends open.The rear end, that is, the base end 41a, is opened by a holding cylinder 42 fitted on the inner peripheral surface of the valve cylinder 25. It is held in close contact with the inner peripheral surface of the cylinder 25.
The valve body 41 includes a thin flexible portion 41b bent inward in the radial direction from the base end portion 41a, and a thick valve portion 41c connected to the front end of the flexible portion 41b. The portion 41c is arranged to face the first and second valve seats 40 ₁ and 40 ₂ .

And Thus, the valve portion 41c be capable of moving back and forth by the deformation of the flexible portion 41b, it is seated on the first and second valve seat 40 _1, 40 ₂ at the time of forward movement, received at the front end of the holding cylinder 42 during retraction Can be stopped.

The valve portion 41c is embedded annular reinforcement plate 43, between the input rod 35 and this, a valve spring 44 which biases the valve portion 41c to both valve seat 40 _1, 40 ₂ are compressed state You.

The inner surface of the valve cylinder 25, one end of the first port 30 on the outside of the first valve seat 40 _1, One end of the second port 31, 31 at the inside of the valve seat 40 ₁ is opened, respectively.

The inside of the second valve seat 40 ₂ communicates with the atmosphere introduction port 33 through the hollow portion of the valve body 41 and the holding cylinder 42.

And Thus, the valve element 41, the control valve 32 is constituted by a valve spring 44, first valve seat 40 ₁ and the second valve seat 40 _2.

In FIG. 1 again, between the input rod 35 and the holding cylinder 42,
A return spring 45 for urging the input rod 35 toward its rear end is contracted.

The backward limit of the input rod 35 is regulated by a stopper plate 46 screwed to the input rod 35 so as to be adjustable forward and backward so as to project on the inner surface of the end wall 26a of the rear extension cylinder 26. Therefore, the stopper plate 46
By turning, the screwing position between the stopper plate 46 and the input rod 35 changes, so that the retraction limit of the input rod 35 can be adjusted back and forth. After the adjustment, the stopper plate 46 is fixed by the input
This is performed by tightening a lock nut 47 screwed to 35. A vent hole 48 is formed in the stopper plate 46 so that the stopper plate 46 does not block the air inlet 33.

An air filter 49 for filtering air taken into the valve cylinder 25 from the air inlet 33 is attached to the valve cylinder 25 around the input rod 35. The air filter 49 includes the input rod 35 and the valve cylinder 25.
It has appropriate flexibility so as not to interfere with relative displacement with.

The piston boss 10 is provided with a large cylinder hole 37 opening at the center of the front surface thereof, and a small cylinder hole 36 opening at both ends in the large cylinder hole 37 and the valve cylinder 25. The small cylinder hole 36 is slidably fitted with a reaction force piston 52 which is in contact with the valve piston 38 or is in contact with the valve piston 38, and the large cylinder hole 37 is provided with an elastic piston 5 facing the reaction piston 52.
0, and the output piston 51 overlapped with the front surface of the elastic piston 50 are slidably fitted together. In order to prevent the output piston 51 from being pulled out from the large cylinder hole 37, the inner peripheral edge of the end wall plate 13a is extended to the opening of the large cylinder hole 37.

An output rod 53 projects from the front surface of the output piston 51. The output rod 53 is a piston 55 of the brake master cylinder M.
Will be serialized.

Next, the operation of this embodiment will be described. First, in the rest state of the negative pressure booster B, as shown in FIG. 1, the input rod 35 is located at the retreat limit, and the control valve 32 moves the valve portion 41c to the first and second valve seats 40 ₁ and 40 ₂ . It is in a neutral state in which the front and rear working chambers 2b, 3b are disconnected from both the negative pressure chambers 2a, 3a and the air introduction port 33 after being seated, and the negative pressure chambers 2a, 2a, Three
In a, the negative pressure of the negative pressure source supplied through the negative pressure introducing pipe 29 is stored, and the negative pressure appropriately diluted by the atmosphere is held in both working chambers 2b and 3b. Thus, a slight forward force is applied to the front and rear booster pistons 4 and 6 by the pressure difference between the front negative pressure chamber 2a and the working chamber 2b and between the rear negative pressure chamber 3a and the working chamber 3b. When these forward forces and the resilient force of the return spring 23 are balanced, the booster pistons 4 and 6 stop when they slightly advance from the retreat limit.

Now, depress the brake pedal 34 to brake the vehicle,
If caused to advance the input rod 35 and the valve piston 38, initially, since both booster pistons 4 and 6 are stationary, the second valve seat 40 ₂ immediately away both working chambers 2b from the valve portion 41c, the 3b atmosphere introduction Connect to mouth 33. As a result, from the atmosphere which has flowed into the valve body 41 from the air introduction port 33 through the second valve seat 40 _2, moves to the second port 31 through the annular groove 38a, both working chambers 2b, 3b, It is introduced quickly and makes the chambers 2b, 3b higher in pressure than the negative pressure chambers 2a, 3a, so that a large forward force based on the pressure difference between them is obtained and the booster pistons 4, 6 resist the force of the return spring 23. Then, the piston 55 of the brake master cylinder M is driven forward via the output rod 53. In this way, the brake master cylinder M can be operated without delay when the brake pedal 34 is depressed to brake the vehicle.

During such braking, the valve piston 38 moves forward together with the input rod 35 and abuts on the elastic piston 50 via the reaction force piston 52.
Receiving the operation reaction force, swells and deforms toward the small cylinder hole 36 to cause a part of the reaction force to act on the reaction force piston 52, and the force is applied to the brake pedal via the valve piston 38 and the input rod 35.
Feedback to the 34 side. The operator can sense the output of the output rod 53, that is, the magnitude of the braking force by the reaction force.

When the output of the output rod 53 exceeds the boosting limit point due to the increase in the input force of the input rod 35, the pedaling force on the brake pedal 34,
Since the front surface of the valve piston 38 is in contact with the piston boss 10, the entire input is transmitted to the output rod 53 via the valve piston 38, the piston boss 10, the elastic piston 50, and the output piston 51. The sum of the forward force due to the pressure difference between the booster pistons 4 and 6 and the forward force due to the input is the output rod 53.
Output from

Next, when the pedaling force on the brake pedal 34 is released,
First, the input rod 35 is moved by the spring force of the return spring 45 to the valve piston 38.
With this, the second valve seat 40 ₂ is seated on the valve portion 41c of the valve body 41, and the valve portion 41c is largely separated from the first valve portion 40 _1, so that both working chambers 2b and 3b have the first and second working chambers 2b and 3b. It communicates with both negative pressure chambers 2a and 3a through ports 30 and 31.

Then, due to the strong suction action of the negative pressure source V connected to the front negative pressure chamber 2a, the air occupying both working chambers 2b and 3b until now is axially directed from the second port 31, 31 to the first port 30. Port 3
After being rapidly sucked into the front negative pressure chamber 2a through 0A, the pressure difference between the booster pistons 4 and 6 disappears, and as a result,
The booster pistons 4 and 6 are retracted by the elastic force of the return spring 23 and release the operation of the brake master cylinder M.

By the way, the air exiting the second ports 31 and 31 is the first port 3
When the axial port 30A of 0 flows at high speed from the valve cylinder 25 side to the front negative pressure chamber 2a side, the disturbance in the axial port 30A itself is related to the fact that the axial port 30A is substantially linear. Generation of flow and vortex is suppressed as much as possible. Also, at this time, even if part of the high-speed air flow that flows in a substantially straight line tries to go around to the radial port 30R, the radial port 30R of the half portion of the circumferential wall of the axial port 30A on the outer side in the radial direction of the piston boss. As described above, since the step 1 is formed between the front side portion 30Af and the rear side portion 30Ar of the axial port 30A side opening edge, the above-mentioned air flow trying to go around the radial direction port 30R is , With its inertial force, the above-mentioned fifth air flow is
With its inertial force, it easily jumps over the radial port 30R as shown by the arrow in FIG. 5 and the front side portion of the axial port 30A.
Flows smoothly to the 30Af side, thus radial port
Generation of vortices near the opening of 30R is also suppressed, and wind noise does not occur.

When the input rod 35 returns to the retreat limit where the stopper plate 46 contacts the partition 26a of the extension cylinder 26, the rear booster piston 6
As shown in FIG. 4, the projection 24 of the rear diaphragm 7 is
Back to the rear end of contacting the rear wall of the booster shell 1 with the first valve seat 40 ₁ seated on the valve seat 41c and the valve portion 41c slightly separated from the second valve seat 40 ₂ again. Atmosphere is introduced into both working chambers 2b and 3b, but if the booster pistons 4 and 6 slightly advance due to the pressure difference caused thereby, the small gap between the second valve seat 40 ₂ and the valve portion 41c disappears, and control is performed. Bring valve 32 to the initial neutral state. Thus, both working chambers 2b, 3b
Negative pressure diluted in the atmosphere is held in the negative pressure booster B
Is in the rest state shown in FIG.

FIG. 6 shows a second embodiment of the present invention. In addition to the configuration of the previous embodiment, the radial port 30R has an axial port 30A.
The valve cylinder 25 side portion e ₁ of the side opening edge is projected in a shelf shape toward the front negative pressure chamber 2a side portion e ₂ . By doing so, the jumping effect of the air flowing through the axial port 30A on the radial port 30R can be improved. In FIG. 6, parts corresponding to those in the previous embodiment are designated by the same reference numerals.

C. Effect of the Invention As described above, according to the present invention, the axial port of the first port is formed in a substantially linear shape over the entire length, and the half portion of the peripheral wall of the axial port on the outer side in the radial direction of the piston boss. Of the radial ports, the front portion of the radial port is more outwardly displaced in the radial direction than the rear portion of the axial port side opening edge, and a step is provided in both portions, so that the air flows through the axial port. When flowing at high speed from the cylinder side to the front negative pressure chamber side, the generation of turbulence or vortex in the axial port itself can be suppressed as much as possible, because the axial port is substantially linear. it can. Moreover, even if a part of the high-speed airflow that flows in a substantially straight line tries to go around to the radial port, it easily jumps over the radial port due to the presence of the step, and is smooth to the downstream side of the axial port, that is, the front side portion. Since it is possible to move to the radial port, it is possible to suppress the wraparound of the air to the radial port and the generation of the vortex near the opening of the radial port as much as possible. It is possible to extremely effectively prevent the generation of wind noise due to the noise, and contribute to reducing the operating noise of the negative pressure booster.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a vertical side view of a tandem type negative pressure booster in a rest state, and FIGS. 2 and 3 are II-II line and III- of FIG. III sectional view, 4th
FIG. 5 is a partial vertical cross-sectional side view showing a state immediately before the negative pressure booster finishes its operation and returns to a rest state, and FIG. 5 is an operational explanatory view (V-V in FIG. 2) in which an essential part of the negative pressure booster is enlarged. FIG. 6 is a sectional view similar to FIG. 5 showing a second embodiment of the present invention, and FIG. 7 is a sectional view showing an essential part of a conventional tandem type negative pressure booster. B ... Negative pressure booster, l ... Step, 1 ... Booster shell, 1c ... Partition plate, 2a, 3a ... Front and rear negative pressure chambers, 2b, 3b ...
… Front and rear working chambers, 4,6 …… Front and rear booster pistons, 10 …… Piston boss as boss, 25 …… Valve cylinder,
30 …… First port, 30A …… Axial port, 30Af …… Front part, 30Ar …… Rear part, 30R …… Radial port, 3
1 …… Second port, 32 …… Control valve, 33 …… Atmosphere inlet, 3
5 …… input rod, 53 …… output rod

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoshiharu Nagato 840 Kokubu, Ueda City, Nagano Prefecture Nisshin Kogyo Co., Ltd. (56) References 60-137666 (JP, U) Actual 58- 111666 (JP, U) Actual development Sho 60-125270 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] A partition plate (1c) for partitioning the interior of the booster shell (1) into a front shell chamber (2) and a rear shell chamber (3) is fixed to the front shell chamber (2). The front booster piston (4) which divides the front front negative pressure chamber (2a) connected to the negative pressure source into the rear front working chamber (2b) and the rear shell chamber (3) are connected to the front rear negative chamber. A rear booster piston (6) which divides the pressure chamber (3a) and the rear working chamber (3b) on the rear side;
The output rod (53) is slidably supported by the partition plate (1c).
Via a piston boss (10) connected to the valve boss (10), and a valve cylinder (25) projecting from the rear end and slidably supported by the rear wall of the booster shell (1) is integrally formed with the piston boss (10). The valve cylinder (25) is connected to both negative pressure chambers (2
a) and a second port (31) that communicates with the inside of the valve cylinder (25) to both working chambers (2b, 3b). ) Is an axial port (30A) that communicates between the front negative pressure chamber (2a) and the valve cylinder (25), and a radial port (30A) that communicates between this axial port (30A) and the rear negative pressure chamber (3b). 30R), and an input rod (35) that can be moved back and forth in the valve cylinder (25), and a second port (31) is connected to the first port (30) according to the forward and backward movement of the input rod (35). ) And a control valve (32) for switching communication with the atmosphere, in the tandem type negative pressure booster, the axial port (30A) is formed substantially linearly over its entire length, and the axial port (30A) ) Of the peripheral wall of the outer peripheral portion of the piston boss in the radial direction, the axial port (30R) of the radial port (30R).
A portion (30Af) on the front side of the opening edge on the side A) is deviated to the outer side in the radial direction from the rear portion (30Ar), and a step (l) is provided between both portions (30Af, 30Ar). A tandem type negative pressure booster characterized in that